In some seat pad used for a seat equipped with transportation such as a vehicle, a ship, and an aircraft, for a chair of furniture or similar chair, and the like, an inner pad and a pad main body, which have mutually different characteristics, are integrally foam molded (for example, Patent Literature 1). A description will be given of a conventional seat pad 101 disclosed in Patent Literature 1 with reference to FIGS. 8A-C. FIG. 8A is a cross-sectional view of an inner pad 102, which constitutes a part of the conventional seat pad 101. FIG. 8B is a cross-sectional view of a molding die 110 where a pad main body 103 is to be foam molded. FIG. 8C is a cross-sectional view of the seat pad 101 foam molded integrally with a back-side reinforced fabric 104. The following describes the seat pad 101 to be used in a seat for an automobile.
As illustrated in FIG. 8A, the seat pad 101 is a flexible pad arranged between a seat spring and an epidermis material (neither of which is illustrated). The seat spring is disposed in a vehicle body of the automobile. The seat pad 101 is constituted to include the inner pad 102 (synthetic resin foam) made of foamed synthetic resin, the pad main body 103 (synthetic resin foam) made of foamed synthetic resin, and the back-side reinforced fabric 104 such as a nonwoven fabric. The pad main body 103 covers the front side (the upper side in FIG. 8C) of the inner pad 102. The back-side reinforced fabric 104 is arranged on the back side of the pad main body 103 and the inner pad 102.
Both the inner pad 102 and the pad main body 103 are formed of a flexible foam made of synthetic resin, for example, a flexible polyurethane foam or a semi-rigid polyurethane foam, and are set to have mutually different characteristics. The back-side reinforced fabric 104 is a seat pad member that is constituted of a nonwoven fabric (such as a hair felt) or similar material and that is integrally foamed. When the seat pad 101 is used in a seat for an automobile, the back-side reinforced fabric 104 is interposed between: a seat spring and a seat component (neither of which is illustrated); and the inner pad 102 and the pad main body 103.
The following describes a method for manufacturing the seat pad 101. Firstly, as illustrated in FIG. 8A, the inner pad 102 foam molded by a molding die (not illustrated) is prepared. Subsequently, as illustrated in FIG. 8B, the back-side reinforced fabric 104 and the inner pad 102 are mounted by a magnet, a pin, or similar method within the molding die 110 for foam molding the pad main body 103.
Here, the molding die 110 is constituted to include a lower die 111 and an upper die 114. The lower die 111 is a member in approximately a box shape whose top portion is opened. In the lower die 111, a molding surface 112 is formed. The molding surface 112 molds the front side of the pad main body 103. At the peripheral edge of the molding surface 112, a parting surface 113 is formed. The upper die 114 is a member formed in a lid shape that can seal the molding surface 112 of the lower die 111. At the peripheral edge of a molding surface 115, which molds the back side of the pad main body 103, a parting surface 116 is formed. The parting surface 116 becomes the matching surface with the lower die 111.
The back-side reinforced fabric 104 is mounted on the molding surface 115 of the upper die 114 constituted as described above. The inner pad 102 is mounted on the upper die 114 to be overlapped with the back-side reinforced fabric 104. A foamed synthetic resin material P (liquid raw material), which is a raw material of the pad main body 103, is injected into the lower die 111. The parting surfaces 113 and 116 are matched for closing the dies. Subsequently, the foamed synthetic resin material P is foamed. After curing for a predetermined time, the dies are opened to demold the molded seat pad 101.
When the pad main body 103 is foam molded, the foamed synthetic resin material P is impregnated in the back-side reinforced fabric 104 and the front side of the inner pad 102. Accordingly, the pad main body 103 is bonded integrally with the back-side reinforced fabric 104 and the front side of the inner pad 102. The back-side reinforced fabric 104, which is hardened by impregnation of the foamed synthetic resin material P, has a high hardness. Thus, the back-side reinforced fabric 104 becomes a receiving member for the seat spring and the seat component (neither of which is illustrated).